The pointing stick operates by sensing applied force, by using a pair of resistivestrain gauges. A pointing stick can be used by pushing with the fingers in the general direction the user wants the cursor to move. The velocity of the pointer depends on the applied force so increasing pressure causes faster movement. The relation between pressure and cursor or pointer speed can be adjusted, similar to the way the mouse speed is adjusted in a traditional desktop computer.

On a QWERTY keyboard, the stick is typically embedded between the "G", "H" and "B" keys, and the mouse buttons are placed just below the space bar. The mouse buttons can be operated right-handed or left-handed due to their placement below the keyboard along the centerline. This pointing device has also appeared next to screens on compact-sized laptops such as Toshiba Libretto, Sony VAIO UX, etc.

Pointing sticks typically have a replaceable rubber cap, called a nub, which can be a slightly rough "eraser head" material (Classic Dome) or another shape (Soft Dome or Soft Rim, or concaved shaped c).[1]

The cap is red on ThinkPads, but is also found in other colours on other machines. For example, it may be grey, black or blue on some Dell models, and blue on some HP/Compaq laptops.

In the early 1990s, Zenith Data Systems shipped a number of laptop computers equipped with a device called "J-Mouse", which essentially used a special keyswitch under the J key to allow the J keycap to be used as a pointing stick.

In addition to appearing between the g, h and b keys on a qwerty keyboard, these devices or similar can also appear on gaming devices as an alternative to a D-pad or analog stick. On a certain Toshiba Libretto mini laptop, the pointing stick was located next to the display. IBM sold a mouse with a pointing stick in the location where a scroll wheel is common now.

Optical pointing sticks are also used on some ultrabook tablet hybrids, such as the Sony Duo 11, ThinkPad Tablet and Samsung Ativ Q.

A similar technology is used on the C Stick featured on the New Nintendo 3DS.

The user can often customize the operation of pointing sticks using software.

The user may be able to adjust the sensitivity of the pointing stick, so that application of a given amount of force moves the pointer a greater or smaller distance across the screen.

On some systems a user may be able to configure an option to enable "press-to-select", in which a sharp tap on the pointing stick is equivalent to a click of a specified mouse button.

Other configuration options may include swapping middle mouse functionality to that which allows the pointing stick to act as a scroll wheel while the middle mouse button is held. This is frequently set to default behavior in 2013 computers, and makes the middle mouse button not work with 3d design programs or any program that explicitly uses the middle mouse button to perform functions.

The IBM TrackPoint III and the TrackPoint IV have a feature called Negative Inertia that causes the pointer's velocity to "overreact" when it is accelerated or decelerated. Negative Inertia is intended to avoid feeling of inertia or sluggishness when starting or stopping movement.[2] Usability tests at IBM have shown that it is easier for users to position the pointer with Negative Inertia, and performance is 7.8% better.[3]

Another challenge with pointing stick design is identification of the zero position (the position where no motion is desired). Because the amount of motion is small, the sensitivity of the sensors must be high, and they are subject to noise interference.

A typical solution, which assumes that pointing sticks frequently go out of calibration, is to interpret a variation below a certain threshold (over a given interval, perhaps one or several seconds) as being a neutral stick.

In practice, if the re-calibration interval is set too short and if the user applies moderately consistent pressure to the stick for such an interval, this method results mistakenly re-zeroed the stick and the pointer stops. Additional pressure again moves the cursor, but the calibration may occur again, requiring even more force. If the user releases pressure at this point, the change will be interpreted as an instruction to move the opposite direction. In time, the software will re-calibrate and stop the motion.

Additionally, if "press-to-select" is enabled (see above), the software may generate unexpected click events by touching the pointing stick during typing.

Since ThinkPad computers have a nub that is responsive to pressure in a direction, and there is a patent for this[citation needed] other companies have made it so a person has to move the finger a large distance to cause the nub to rock from side to side in a much less efficient way.

In 1984, Ted Selker, a researcher at PARC, worked on a pointing stick based on a study[citation needed] that a typist needs a relatively long 0.75 sec to shift the hand from the keyboard to the mouse, and comparable time to shift back. Selker built a model of a device that would minimize this time. It was only three years later, working at IBM, that Selker refined his design, resulting in the TrackPoint product[4] for which IBM received US patents in 1996.[5][6]

Some users feel that pointing sticks cause less wrist strain, because user does not need to avoid resting wrists on a touchpad, usually located just below the keyboard[citation needed]. One criticism is that because the pointing stick depends on the user applying pressure, it can cause hand cramps (although this can be partly solved by setting the sensitivity to high, and lifting the finger when the pointer is not being moved). Another criticism is that it stresses the index finger and may lead to repetitive strain injury.

A number of ergonomic studies to compare trackpoint and touchpad performance have been performed.[9][10] Most studies find that touchpad is slightly faster; one study found that "the touchpad was operated 15% faster than the trackpoint".[11] Another study found that average object selection time was faster with a touchpad, 1.7 sec compared to 2.2 sec with a trackpoint, and object manipulation took 6.2 sec with a touchpad, on average, against 8.1 sec with trackpoint.[12]